The rapid miniaturization in electronic devices, particularly their manufacture and assembly, has transformed the medical industry. In particular, handling and testing of cells and other components within body fluids has moved beyond the conventional test tube to other devices, such as biochips. A biochip, sometimes called a lab-on-a-chip, refers to the placement of biologic materials on a miniature electronic device that is capable of electrically and/or chemically interacting with the biologic materials for testing or other purposes.
Considerable efforts have been made in the biochip environment to apply electric fields to manipulate cells, including their movement, separation, property determination, etc. Despite numerous attempts at cell manipulation with electric fields, the ability to manipulate cells is still limited by different characteristics of the cells, such as cell size, cell aggregation, cell polarizability, etc. For example, enriching one type of cells from other types of cells is challenged by the great variety of sizes, shapes, polarizability, and relative volumes of cells within a fluid. Impeding the enrichment of certain types of cells on the biochip, in turn, hampers the ability to perform other functions on those cells, such as testing, harvesting, and processing for further analyses.
For these reasons, among others, widespread use of biochip devices has been limited.